Former No. 1-ranked player Kim Clijsters announced her return to the tennis circuit Thursday after two years in retirement.

"The hunger is back," the 25-year-old Belgian said. "I look forward to the challenge."

Clijsters, who retired in May 2007 to get married and start a family, announced her comeback at the tennis facility in Bree, Belgium, where she has been practicing recently.

She said she has already asked for wild cards for hard-court tournaments in Cincinnati and Toronto in August and the U.S. Open.

"I want to be back at my peak as soon as possible, but I know that is not logical to ask that," Clijsters said. "I will have to take it match by match."

Clijsters won the 2005 U.S. Open for her one Grand Slam title. She won 34 career titles overall and was runner-up in four Grand Slam finals.

Rising to the top at the same time as another Belgian who retired early, Justine Henin, Clijsters held the No. 1 singles ranking for 19 weeks.

Her career was marred by a series of injuries, including to her hip and back.

Clijsters, who gave birth to a daughter last year, returns at a time when the WTA tour is wide open and without a single player dominating the rankings.

Clijsters was already set to join Steffi Graf, Andre Agassi and Tim Henman for a series of exhibition matches at Wimbledon on May 17 to test conditions under the new retractable roof on Centre Court.

She also is scheduled to play an exhibition June 14 against Michaella Krajicek in the Netherlands, along with two matches for the St. Louis Aces of World Team Tennis in July.